Innate Immune Defences & Inflammation 1 Flashcards

Question

_Innate Barriers to Infection_ * Physical barriers - skin, respiratory tract, gastrointestinal tract * Soluble - Complement, Defensins, ... * Induced - Innate Immune cells, Pattern Recognition Receptors (PRRs), Interferon

Answer 1

* Physical barriers - skin, respiratory tract, gastrointestinal tract * Soluble - Complement, Defensins, **Collectins** * Induced - Innate Immune cells, Pattern Recognition Receptors (PRRs), Interferon

Answer 2

**Innate barriers to infection**

Answer 3

**Innate barriers to infection**

Answer 4

* Skin has a dense layer of dead **keratinocytes** that act as a physical barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by Cystic fibrosis). In the lower airways there are collectins in the **surfactant** that can activate complement. * In the gut, people unable to secrete sufficient gastric acid have a high risk of salmonella infection. * In the airway and lungs, sneezing and coughing help to expel mucus, whilst macrophages in the alveoli of the lungs can ingest pathogens. * The intestine is colonised with ‘good’ bacteria that form your microbiome.

Answer 5

* Skin has a dense layer of dead keratinocytes that act as a **physical** barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by Cystic fibrosis). In the lower airways there are collectins in the surfactant that can activate complement. * In the gut, people unable to secrete sufficient gastric acid have a high risk of salmonella infection. * In the airway and lungs, sneezing and coughing help to expel **mucus**, whilst macrophages in the alveoli of the lungs can ingest pathogens. * The intestine is colonised with ‘good’ bacteria that form your microbiome.

Answer 6

* Skin has a dense layer of dead keratinocytes that act as a physical barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by Cystic fibrosis). In the lower airways there are collectins in the surfactant that can activate **complement**. * In the gut, people unable to secrete sufficient gastric acid have a high risk of **salmonella** infection. * In the airway and lungs, sneezing and coughing help to expel mucus, whilst macrophages in the alveoli of the lungs can ingest pathogens. * The intestine is colonised with ‘good’ bacteria that form your microbiome.

Answer 7

* Skin has a dense layer of dead keratinocytes that act as a physical barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by Cystic fibrosis). In the lower airways there are collectins in the surfactant that can activate complement. * In the gut, people unable to secrete sufficient gastric acid have a high risk of salmonella infection. * In the airway and lungs, sneezing and coughing help to expel mucus, whilst **macrophages** in the alveoli of the lungs can ingest pathogens. * The intestine is colonised with ‘good’ bacteria that form your **microbiome**.

Answer 8

* Skin has a dense layer of dead keratinocytes that act as a physical barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by **Cystic fibrosis)**. In the lower airways there are collectins in the surfactant that can activate complement. * In the gut, people unable to secrete sufficient gastric acid have a high risk of salmonella infection. * In the airway and lungs, sneezing and coughing help to expel mucus, whilst macrophages in the alveoli of the lungs can ingest pathogens. * The intestine is **colonised** with ‘good’ bacteria that form your microbiome.

Answer 9

* Skin has a dense layer of dead **keratinocytes** that act as a physical barrier. * In the respiratory tract mucus traps micro-organisms (importance demonstrated by Cystic fibrosis). In the lower airways there are **collectins** in the surfactant that can activate complement. * In the gut, people unable to secrete sufficient gastric acid have a high risk of salmonella infection. * In the airway and lungs, sneezing and coughing help to expel mucus, whilst macrophages in the alveoli of the lungs can ingest pathogens. * The intestine is colonised with ‘good’ bacteria that form your microbiome.

Answer 10

* Tissue resident cells detect the infection and release **soluble** innate immune effectors and cytokines to cause vasodilation and recruitments of further innate immune cells.

Answer 11

* Tissue resident cells detect the infection and release soluble innate immune effectors and **cytokines** to cause vasodilation and recruitments of further innate immune cells.

Answer 12

* Tissue resident cells detect the infection and release soluble innate immune **effectors** and cytokines to cause **vasodilation** and recruitments of further innate immune cells.

Answer 13

* **Enzymes** such as Lysozyme * Disrupt bacterial cell walls; found in blood and tears * Antimicrobial **peptides** * Disrupt microbial membranes * Collectins, ficolins and pentraxins * Bind to pathogens targeting them for phagocytosis and activate complement * Complement components * Lyse bacteria, opsonise bacteria and induce inflammation

Answer 14

* Enzymes such as Lysozyme * Disrupt bacterial cell **walls**; found in blood and tears * **Antimicrobial** peptides * Disrupt microbial membranes * Collectins, ficolins and pentraxins * Bind to pathogens targeting them for **phagocytosis** and activate complement * Complement components * Lyse bacteria, opsonise bacteria and induce inflammation

Answer 15

* Enzymes such as Lysozyme * Disrupt bacterial cell walls; found in blood and tears * Antimicrobial peptides * Disrupt microbial membranes * Collectins, ficolins and pentraxins * Bind to pathogens targeting them for phagocytosis and activate **complement** * **Complement** components * Lyse bacteria, opsonise bacteria and induce inflammation

Answer 16

* Enzymes such as Lysozyme * Disrupt bacterial cell walls; found in blood and tears * Antimicrobial peptides * Disrupt microbial membranes * Collectins, ficolins and pentraxins * Bind to **pathogens** targeting them for phagocytosis and activate complement * Complement components * Lyse bacteria, **opsonise** bacteria and induce inflammation

Answer 17

* Enzymes such as Lysozyme * Disrupt bacterial cell walls; found in blood and tears * Antimicrobial peptides * Disrupt microbial **membranes** * Collectins, ficolins and pentraxins * Bind to pathogens targeting them for phagocytosis and activate complement * Complement components * Lyse bacteria, opsonise bacteria and induce **inflammation**

Answer 18

* Enzymes such as Lysozyme * Disrupt bacterial cell walls; found in **blood** and **tears** * Antimicrobial peptides * Disrupt microbial membranes * **Collectins**, ficolins and pentraxins * Bind to pathogens targeting them for phagocytosis and activate complement * Complement components * Lyse bacteria, opsonise bacteria and induce inflammation

Answer 19

These are all examples of **soluble innate** immune molecules

Answer 20

make (a foreign cell) more susceptible to phagocytosis.

Answer 21

* Lysozyme is secreted by phagocytes and **paneth** cells from the small intestine * Lysozyme is most effective against gram positive bacteria because LPS masks peptidoglycan in gram negative bacteria. * Cleaves the bond between the alternating sugars that make up peptidoglycan * Phospholipase A2 hydrolyses phospholipids in cell membrane to kill bacteria

Answer 22

* Lysozyme is secreted by phagocytes and paneth cells from the small intestine * Lysozyme is most effective against gram **positive** bacteria because LPS masks peptidoglycan in gram **negative** bacteria. * Cleaves the bond between the alternating sugars that make up peptidoglycan * Phospholipase A2 hydrolyses phospholipids in cell membrane to kill bacteria

Answer 23

* Lysozyme is secreted by phagocytes and paneth cells from the small intestine * Lysozyme is most effective against gram positive bacteria because LPS masks peptidoglycan in gram negative bacteria. * **Cleaves** the bond between the alternating sugars that make up peptidoglycan * Phospholipase **A2** hydrolyses phospholipids in cell membrane to kill bacteria

Answer 24

Lysozyme is most effective against gram **positive** bacteria because LPS masks peptidoglycan in gram **negative** bacteria.

Answer 25

* **Histatins** * Produced in the oral cavity. Active against pathogenic fungi, e.g. Candida albicans * Cathelicidins * LL-37 broad-spectrum antimicrobial activity against both Gram-negative and Gram-positive bacteria * Defensins * 2 classes - alpha, beta defensins

Answer 26

* Histatins * Produced in the **oral** cavity. Active against pathogenic fungi, e.g. Candida albicans * Cathelicidins * LL-37 broad-spectrum antimicrobial activity against both Gram-negative and Gram-positive bacteria * **Defensins** * 2 classes - alpha, beta **defensins**

Answer 27

* Histatins * Produced in the oral cavity. Active against pathogenic fungi, e.g. Candida albicans * **Cathelicidins** * LL-37 broad-spectrum antimicrobial activity against both Gram-negative and Gram-positive bacteria * Defensins * 2 classes - alpha, beta defensins

Answer 28

* Histatins * Produced in the oral cavity. Active against pathogenic fungi, e.g. Candida albicans * Cathelicidins * LL-**37** broad-spectrum antimicrobial activity against both Gram-negative and Gram-positive bacteria * Defensins * 2 classes - **alpha, beta** defensins

Answer 29

* 3 families - Histatins, Cathlicidins, Defensins * Cover epithelial surfaces, found in **saliva** * Constitutively secreted by neutrophils, epithelial cells and paneth cells in the crypts of the small intestine * Kill bacteria in minutes, by disrupting the membrane * Also attack fungi, viruses (influenza and herpes virus) * Inhibit DNA and RNA synthesis

Answer 30

* 3 families - Histatins, Cathlicidins, Defensins * Cover epithelial surfaces, found in saliva * Constitutively secreted by **neutrophils**, epithelial cells and **paneth** cells in the crypts of the small intestine * Kill bacteria in minutes, by disrupting the membrane * Also attack fungi, viruses (influenza and herpes virus) * Inhibit DNA and RNA synthesis

Answer 31

* 3 families - Histatins, Cathlicidins, Defensins * Cover epithelial surfaces, found in saliva * Constitutively secreted by neutrophils, epithelial cells and paneth cells in the crypts of the small intestine * Kill bacteria in **minutes**, by disrupting the membrane * Also attack fungi, viruses (influenza and herpes virus) * Inhibit DNA and RNA synthesis

Answer 32

* 3 families - Histatins, Cathlicidins, Defensins * Cover **epithelial** surfaces, found in saliva * Constitutively secreted by neutrophils, epithelial cells and paneth cells in the crypts of the small intestine * Kill bacteria in minutes, by disrupting the membrane * Also attack fungi, viruses (influenza and herpes virus) * Inhibit DNA and RNA synthesis

Answer 33

* 3 families - Histatins, Cathlicidins, Defensins * Cover epithelial surfaces, found in saliva * Constitutively secreted by neutrophils, epithelial cells and paneth cells in the crypts of the small intestine * Kill bacteria in minutes, by disrupting the membrane * Also attack fungi, viruses (influenza and herpes virus) * Inhibit **DNA** and **RNA** synthesis

Answer 34

* 3 families - Histatins, Cathlicidins, Defensins * Cover epithelial surfaces, found in saliva * Constitutively secreted by neutrophils, epithelial cells and paneth cells in the crypts of the small intestine * Kill bacteria in minutes, by disrupting the membrane * Also attack **fungi, viruses** (influenza and herpes virus) * Inhibit DNA and RNA synthesis

Answer 35

in minutes - slowest takes 90 mins

Answer 36

fungi and viruses (influenza and herpes virus)

Answer 37

Antimicrobial peptides inhibit **DNA** and **RNA** synthesis

Answer 38

**Defensins** cover our epithelial surfaces and are present in the vernix caseosa and in the skin of the healthy new born

Answer 39

Defensins cover our epithelial surfaces and are present in the vernix caseosa and in the skin of the **healthy new born**

Answer 40

The only human cathelicidin is **LL37**, a peptide of **37** amino acids synthesized by macrophages, neutrophils, and epithelial cells (providing antimicrobial protection to our skin and the lining of our urinary tract).

Answer 41

* **35-40** aa amphipathic peptides which means they have both hydrophilic and hydrophobic regions on their cell surface. * Disulphide bonds stabilise the structure to have a positively charged region separated from a hydrophobic region * Disrupt microbial membranes but not that of the host

Answer 42

* 35-40 aa **amphipathic** peptides which means they have both hydrophilic and hydrophobic regions on their cell surface. * Disulphide bonds stabilise the structure to have a positively charged region separated from a hydrophobic region * Disrupt microbial membranes but not that of the **host**

Answer 43

Defensins - **Disulphide** bonds stabilise the structure to have a positively charged region separated from a hydrophobic region

Answer 44

Defensins are amphipathic, i.e. they have **positive** charge separated from a **hydrophobic** region.

Answer 45

* Collectins have globular lectin like heads that bind bacterial cell surface sugars. **Sialic** acid hides mannose antigens on host cells. * Ficolins (have a Fibrinogen like domain) recognise **acylated** compounds (COCH3) such as n-acetylglucosamine, a monosaccharide found in bacterial cell walls * Pentraxins are cyclic multimeric proteins in the plasma. C-reactive protein (CRP) is used as a clinical measure of inflammation – CRP binds to phosphocholine on bacterial surfaces

Answer 46

* Collectins have globular lectin like heads that bind bacterial cell surface sugars. Sialic acid hides **mannose** antigens on host cells. * Ficolins (have a Fibrinogen like domain) recognise acylated compounds (COCH3) such as n-acetylglucosamine, a monosaccharide found in bacterial cell walls * Pentraxins are cyclic multimeric proteins in the plasma. **C-reactive** protein (**CRP**) is used as a clinical measure of inflammation – **CRP** binds to phosphocholine on bacterial surfaces

Answer 47

* Collectins have globular lectin like heads that bind bacterial cell surface sugars. Sialic acid hides mannose antigens on host cells. * Ficolins (have a **Fibrinogen** like domain) recognise acylated compounds (COCH3) such as n-acetylglucosamine, a monosaccharide found in bacterial cell walls * Pentraxins are cyclic multimeric proteins in the plasma. C-reactive protein (CRP) is used as a clinical measure of inflammation – CRP binds to phosphocholine on bacterial surfaces

Answer 48

* Collectins have globular lectin like heads that bind bacterial cell surface sugars. Sialic acid hides mannose antigens on host cells. * Ficolins (have a Fibrinogen like domain) recognise acylated compounds (COCH3) such as n-acetylglucosamine, a monosaccharide found in bacterial cell walls * Pentraxins are cyclic multimeric proteins in the plasma. C-reactive protein (CRP) is used as a clinical measure of inflammation – CRP binds to **phosphocholine** on bacterial surfaces

Answer 49

Collectins (collagen-containing C-type lectins) are a part of the innate immune system - Found in surfactant (surfactant protein A and D) and serum (MBL) Sialic acid can "hide" mannose antigens on the surface of host cells or bacteria from mannose-binding lectin. This prevents activation of **complement**.

Answer 50

**Collectins** (collagen-containing C-type lectins) are a part of the innate immune system - Found in surfactant (surfactant protein A and D) and serum (MBL) Sialic acid can "hide" mannose antigens on the surface of host cells or bacteria from mannose-binding lectin. This prevents activation of complement.

Answer 51

* Soluble **pattern recognition receptors** * Act as opsonins that bind to pathogens and infected cells targeting them for phagocytosis * Activate complement through the classical pathway/lectin pathway

Answer 52

* Soluble pattern recognition receptors * Act as **opsonins** that bind to pathogens and infected cells targeting them for phagocytosis * Activate **complement** through the classical pathway/lectin pathway

Answer 53

* 3 different pathways - **Classical** pathway, **Lectin** pathway, **Alternative** pathway * Converge on C3 convertase leading to downstream events that induce inflammation

Answer 54

* 3 different pathways - Classical pathway, **Lectin** pathway, Alternative pathway * Converge on C3 convertase leading to downstream events that induce **inflammation**

Answer 55

* Series of over **30** proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a cascade of reactions that amplify the signal * When activated, cooperate with other host defense systems to generate inflammation and rapidly remove the pathogen * Most made by the liver but also produced by monocytes, macrophages and epithelial cells of the intestine and urinary tract

Answer 56

* Series of over 30 proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a **cascade** of reactions that **amplify** the signal * When activated, cooperate with other host defense systems to generate inflammation and rapidly remove the pathogen * Most made by the liver but also produced by monocytes, macrophages and epithelial cells of the intestine and urinary tract

Answer 57

* Series of over 30 proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a cascade of reactions that amplify the signal * When activated, cooperate with other host defense systems to generate **inflammation** and rapidly remove the pathogen * Most made by the liver but also produced by monocytes, macrophages and epithelial cells of the intestine and urinary tract

Answer 58

* Series of over 30 proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a cascade of reactions that amplify the signal * When activated, cooperate with other host defense systems to generate inflammation and rapidly remove the pathogen * Most made by the **liver** but also produced by monocytes, macrophages and epithelial cells of the intestine and urinary tract

Answer 59

* Series of over 30 proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a cascade of reactions that amplify the signal * When activated, cooperate with other host defense systems to generate inflammation and rapidly remove the pathogen * Most made by the liver but also produced by **monocytes**, **macrophages** and epithelial cells of the intestine and urinary tract

Answer 60

* Series of over **30** proteins that constantly circulate in blood and fluids that bathe the body tissues * When they detect presence of foreign material, they initiate a cascade of reactions that amplify the signal * When activated, cooperate with other host defense systems to generate inflammation and rapidly remove the pathogen * Most made by the liver but also produced by monocytes, macrophages and epithelial cells of the **intestine** and **urinary** tract

Answer 61

* Circulate as a **pro**-form (**inactive**) in the blood * Numbered in the order they were discovered, not in the order they are activated * Some have proteolytic enzymatic activity * On activation they split into a small and large fragments triggering an amplification cascade * Normally ‘a’ is the small fragment - except c2a

Answer 62

* Circulate as a **pro**-form (**inactive**) in the blood * Numbered in the order they were **discovered**, not in the order they are **activated** * Some have proteolytic enzymatic activity * On activation they split into a small and large fragments triggering an amplification cascade * Normally ‘a’ is the small fragment - except c2a

Answer 63

* Circulate as a **pro**-form (**inactive**) in the blood * Numbered in the order they were discovered, not in the order they are activated * Some have **proteolytic** enzymatic activity * On activation they split into a small and large fragments triggering an amplification cascade * Normally ‘a’ is the small fragment - except c2a

Answer 64

* Circulate as a **pro**-form (**inactive**) in the blood * Numbered in the order they were discovered, not in the order they are activated * Some have proteolytic enzymatic activity * On activation they split into a small and large fragments triggering an amplification cascade * Normally ‘**a**’ is the small fragment - except **c2a**

Answer 65

* Circulate as a pro-form (inactive) in the blood * Numbered in the order they were discovered, not in the order they are activated * Some have proteolytic enzymatic activity * On activation they split into a **small** and **large** fragments triggering an amplification cascade * Normally ‘a’ is the small fragment - except c2a

Answer 66

Complement components - Normally 'a' is the **small** fragment - except c2a

Answer 67

* Immune complexes bind CR1 receptors on the erythrocytes which transport them to phagocytes in the liver and spleen for removal. * Some components are termed anaphylatoxins because they can cause anaphylactic shock (C3a, C4a and C5a). * Changes induced by complement components leads to recruitment immune cells to the site of the infection and increases phagocytic capacity.

Answer 68

* Initiated by **C1** activation * **C1** is a complex of three proteins: C1q, C1r and C1s * The structure **of C1** is dominated by C1q * a large molecule of 18 polypeptides that form six collagen like triple helix structures * This was the first complement pathway to be discovered. * **C1** complex is stabilised by Ca2+ ions.

Answer 69

* Initiated by C1 activation * C1 is a complex of three proteins: C1q**, C1r and C1s** * The structure of C1 is dominated by C1q * a large molecule of 18 polypeptides that form six collagen like triple helix structures * This was the first complement pathway to be discovered. * C1 complex is stabilised by Ca2+ ions.

Answer 70

* Initiated by C1 activation * C1 is a complex of three proteins: C1q, C1r and C1s * The structure of C1 is dominated by **C1q** * a large molecule of 18 polypeptides that form six collagen like triple helix structures * This was the first complement pathway to be discovered. * C1 complex is stabilised by Ca2+ ions.

Answer 71

* Initiated by C1 activation * C1 is a complex of three proteins: C1q, C1r and C1s * The structure of C1 is dominated by C1q * a large molecule of 18 polypeptides that form six collagen like triple helix structures * This was the first complement pathway to be discovered. * C1 complex is stabilised by **Ca2**+ ions.

Answer 72

* Triggered when C1 binds to the **Fc** region of an antibody – antigen complex * C1 must bind at least 2 **FC** domains * IgM is the most efficient at activating complement as it has 5 **Fc** domains. IgG1 and IgG3, and to a lesser extent IgG2 can also activate complement when close together bound to antigen

Answer 73

* Triggered when C1 binds to the Fc region of an antibody – antigen complex * C1 must bind at least **2** FC domains * IgM is the most efficient at activating complement as it has **5** Fc domains. IgG1 and IgG3, and to a lesser extent IgG2 can also activate complement when close together bound to antigen

Answer 74

* Triggered when C1 binds to the Fc region of an antibody – antigen complex * C1 must bind at least **2** FC domains * **IgM** is the most efficient at activating complement as it has **5** Fc domains. IgG1 and IgG3, and to a lesser extent IgG2 can also activate complement when close together bound to antigen

Answer 75

**IgM** is the most efficient at activating complement as it has 5 Fc domains. IgG1 and IgG3, and to a lesser extent IgG2 can also activate complement when close together bound to antigen

Answer 76

IgM is the most efficient at activating complement as it has 5 Fc domains. **IgG1** and **IgG3**, and to a lesser extent **IgG2** can also activate complement when close together bound to antigen (The classical pathway is not activated by IgG4.)

Answer 77

The C1 protein is composed of three different types of subunits called **C1q**, C1r, and **C1s**

Answer 78

One IgM molecule bound to antigen can activate complement, whereas around1000 IgG molecules may be required to get 2 close enough together to both bind to **C1 .**

Answer 79

C1 binding an immune complex allows for a conformational change that exposes the **C1q** binding site.

Answer 80

* Serum IgM cannot bind C1 as it has a **planar** conformation, the shape changes on binding antigen to reveal binding sites for C1q

Answer 81

Serum IgM cannot bind C1 as it has a planar conformation, the shape changes on binding antigen to reveal binding sites for **C1q**

Answer 82

Serum **IgM** cannot bind C1 as it has a planar conformation, the shape changes on binding antigen to reveal binding sites for C1q

Answer 83

* Binding C1q with the Fc domain causes a conformational change in **C1r** * C1s is cleaved and can activate C2 and C4 splitting into their large and small fragments * C3 convertase (C4b2a) can then activate over 200 C3 molecules producing a massive amplification of the signal * C4b, C2a and C3b fragments form the C5 convertase that activates C5 leading to the membrane attack complex

Answer 84

* Binding C1q with the Fc domain causes a conformational change in C1r * **C1s** is cleaved and can activate C2 and C4 splitting into their large and small fragments * C3 convertase (C4b2a) can then activate over 200 C3 molecules producing a massive amplification of the signal * C4b, C2a and C3b fragments form the C5 convertase that activates C5 leading to the membrane attack complex

Answer 85

* Binding C1q with the Fc domain causes a conformational change in C1r * C1s is cleaved and can activate **C2 and C4** splitting into their large and small fragments * C3 convertase (C4b2a) can then activate over 200 C3 molecules producing a massive amplification of the signal * C4b, C2a and C3b fragments form the C5 convertase that activates C5 leading to the membrane attack complex

Answer 86

* Binding C1q with the Fc domain causes a conformational change in C1r * C1s is cleaved and can activate C2 and C4 splitting into their large and small fragments * **C3** convertase (C4b2a) can then activate over 200 **C3** molecules producing a massive amplification of the signal * C4b, C2a and C3b fragments form the C5 convertase that activates C5 leading to the membrane attack complex

Answer 87

* Binding C1q with the Fc domain causes a conformational change in C1r * C1s is cleaved and can activate C2 and C4 splitting into their large and small fragments * C3 convertase (C4b2a) can then activate over 200 C3 molecules producing a massive amplification of the signal * C4b, C2a and C3b fragments form the **C5** convertase that activates **C5** leading to the membrane attack complex

Answer 88

* Binding C1q with the Fc domain causes a conformational change in C1r * C1s is cleaved and can activate C2 and C4 splitting into their large and small fragments * C3 convertase (C4b2a) can then activate over 200 C3 molecules producing a massive amplification of the signal * **C4b, C2a and C3b** fragments form the C5 convertase that activates C5 leading to the membrane attack complex

Answer 89

C3a mediates **inflammation**

Answer 90

* Antibody **independent**, activated by ficolins and mannose binding lectin (MBL) * MBL binds **mannose** residues on carbohydrates and glycoproteins on bacteria and some viruses * Similar downstream mechanism to the classical pathway * Upon binding MBL forms a complex with MASP-1 and MASP-2 (serine proteases) * Active complex cleaves C2 and C4

Answer 91

* Antibody independent, activated by **ficolins** and mannose binding lectin (MBL) * MBL binds mannose residues on carbohydrates and glycoproteins on bacteria and some viruses * Similar downstream mechanism to the classical pathway * Upon binding MBL forms a complex with MASP-1 and MASP-2 (serine proteases) * Active complex cleaves **C2 and C4**

Answer 92

* Antibody independent, activated by ficolins and mannose binding lectin (MBL) * MBL binds mannose residues on carbohydrates and glycoproteins on bacteria and some viruses * Similar downstream mechanism to the classical pathway * Upon binding MBL forms a complex with **MASP-1 and MASP-2** (serine proteases) * Active complex cleaves C2 and C4

Answer 93

* Antibody independent, activated by ficolins and **mannose binding lectin (MBL)** * **MBL** binds mannose residues on carbohydrates and glycoproteins on bacteria and some viruses * Similar downstream mechanism to the classical pathway * Upon binding MBL forms a complex with MASP-1 and MASP-2 (**serine** proteases) * Active complex cleaves C2 and C4

Answer 94

**MBL** is a member of the collectin family that is structurally similar to C1q

Answer 95

MBL is a member of the **collectin** family that is structurally similar to C1q

Answer 96

MBL is a member of the collectin family that is structurally similar to **C1q**

Answer 97

MASP1 and 2 structurally and behaviourally similar to **c1r and c1s.**

Answer 98

People deficient in **MBL** or MASP2 have recurrent respiratory infections in childhood before the adaptive defences develop.

Answer 99

People deficient in MBL or **MASP2** have recurrent respiratory infections in childhood before the adaptive defences develop.

Answer 100

* C3 spontaneous **hydrolyses** into **C3a and C3b** * C3b binds to a cell membrane and factor B, making it susceptible to cleavage by factor D to Bb * C3bBb has a half-life of 5 min, unless it binds the serum protein properdin, which extends it half-life to 30 min by protecting it from proteases * C3b,Bb can hydrolyse more C3 creating more C3b which can amplify the signal

Answer 101

* C3 spontaneous hydrolyses into C3a and C3b * C3b binds to a cell membrane and factor **B**, making it susceptible to cleavage by factor **D** to Bb * C3bBb has a half-life of 5 min, unless it binds the serum protein properdin, which extends it half-life to 30 min by protecting it from proteases * C3b,Bb can hydrolyse more C3 creating more C3b which can amplify the signal

Answer 102

* C3 spontaneous hydrolyses into C3a and C3b * C3b binds to a cell membrane and factor B, making it susceptible to cleavage by factor D to Bb * C3bBb has a half-life of **5** min, unless it binds the serum protein properdin, which extends it half-life to **30** min by protecting it from proteases * C3b,Bb can hydrolyse more C3 creating more C3b which can amplify the signal

Answer 103

* C3 **spontaneous** hydrolyses into C3a and C3b * C3b binds to a cell membrane and factor B, making it susceptible to cleavage by factor D to Bb * C3bBb has a half-life of 5 min, unless it binds the serum protein properdin, which extends it half-life to 30 min by protecting it from proteases * C3b,Bb can hydrolyse more C3 creating more C3b which can **amplify** the signal

Answer 104

The **Alternative** pathway (complement) - Involves four serum proteins: C3, complement factor B (circulates in the blood), factor D (secreted by adipocytes), and properdin (released by monocytes and neutrophils).

Answer 105

The Alternative pathway (complement) - Involves four serum proteins: C3, complement factor **B** (circulates in the blood), factor **D** (secreted by adipocytes), and properdin (released by monocytes and neutrophils).

Answer 106

The Alternative pathway (complement) - Involves four serum proteins: C3, complement factor B (circulates in the blood), factor D (secreted by adipocytes), and **properdin** (released by monocytes and neutrophils).

Answer 107

The Alternative pathway (complement) - Involves four serum proteins: C3, complement factor B (circulates in the **blood**), factor D (secreted by adipocytes), and properdin (released by **monocytes** and **neutrophils**).

Answer 108

* C3 **spontaneous** hydrolyses into C3a and C3b * C3b binds to a cell membrane and factor B, making it susceptible to cleavage by factor D to Bb * C3bBb has a half-life of 5 min, unless it binds the serum protein **properdin**, which extends it half-life to 30 min by protecting it from proteases * C3b,Bb can hydrolyse more C3 creating more C3b which can **amplify** the signal

Answer 109

* MAC forms a **pore** that inserts into the membrane allowing diffusion of ions and small molecules, **water** moves into the cell killing it * Human cells have soluble and cell surface associated proteins that prevent MAC formation

Answer 110

* MAC forms a pore that inserts into the membrane allowing diffusion of ions and small molecules, water moves into the cell killing it * **Human** cells have soluble and cell surface associated proteins that prevent MAC formation

Answer 111

* Unwanted **inflammation** if no inhibitors * Hereditary Angioedema : C1 inhibitor deficiency * Classical complement cascade easily activated but can be treated with an injection of C1 inhibitor

Answer 112

* Unwanted inflammation if no inhibitors * Hereditary Angioedema : **C1** inhibitor deficiency * Classical complement cascade easily activated but can be treated with an injection of **C1** inhibitor

Answer 113

Hereditary **Angioedema** : C1 inhibitor deficiency

Answer 114

Hereditary Angioedema : **C1** inhibitor deficiency

Answer 115

* Patients deficient of components of the complement pathway experience **recurrent** **infections** * MBL deficiency causes serious pyogenic infections in neonates and children * C3 deficiency is the most severe leading to successive severe infections * Patients deficient of C8 are prone to infection with Neisseria meningitis

Answer 116

* Patients deficient of components of the complement pathway experience recurrent infections * **MBL** deficiency causes serious pyogenic infections in neonates and children * C3 deficiency is the most severe leading to successive severe infections * Patients deficient of C8 are prone to infection with Neisseria meningitis

Answer 117

* Patients deficient of components of the complement pathway experience recurrent infections * MBL deficiency causes serious pyogenic infections in neonates and children * **C3** deficiency is the most severe leading to successive severe infections * Patients deficient of C8 are prone to infection with Neisseria meningitis

Answer 118

* Patients deficient of components of the complement pathway experience recurrent infections * MBL deficiency causes serious pyogenic infections in neonates and children * C3 deficiency is the most severe leading to successive severe infections * Patients deficient of **C8** are prone to infection with Neisseria meningitis

Answer 119

Patients deficient of C8 are prone to infection with Neisseria **meningitis**

Answer 120

Patients deficient of **C8** are prone to infection with Neisseria meningitis

Answer 121

**C3** deficiency is the most severe leading to successive severe infections

Answer 122

MBL deficiency causes serious **pyogenic** infections in neonates and children

Answer 123

**MBL** deficiency causes serious pyogenic infections in neonates and children

Answer 124

MBL deficiency causes serious pyogenic infections in **neonates and children**

Answer 125

* **90**% of people deficient for C4 develop the autoimmune disease systemic lupus erythematosus (SLE) * C4 deficiency means less C3b (C4b2a is C3 convertase) * C3b bound to immune complexes binds to CR1 on erythrocytes which transports them to phagocytes in the liver and spleen. * Phagocytes recognise the immune complexes via their Fc receptors and engulf them

Answer 126

* 90% of people deficient for C4 develop the autoimmune disease systemic **lupus erythematosus** (SLE) * C4 deficiency means less C3b (C4b2a is C3 convertase) * C3b bound to immune complexes binds to CR1 on erythrocytes which transports them to phagocytes in the liver and spleen. * Phagocytes recognise the immune complexes via their Fc receptors and engulf them

Answer 127

* 90% of people deficient for **C4** develop the autoimmune disease systemic lupus erythematosus (SLE) * **C4** deficiency means less C3b (C4b2a is C3 convertase) * C3b bound to immune complexes binds to CR1 on erythrocytes which transports them to phagocytes in the liver and spleen. * Phagocytes recognise the immune complexes via their Fc receptors and engulf them

Answer 128

* 90% of people deficient for C4 develop the autoimmune disease systemic lupus erythematosus (SLE) * C4 deficiency means less C3b (C4b2a is C3 convertase) * C3b bound to immune complexes binds to CR1 on erythrocytes which transports them to phagocytes in the **liver** and **spleen**. * Phagocytes recognise the immune complexes via their **Fc** receptors and engulf them

Answer 129

**90**% of people deficient for C4 develop the autoimmune disease systemic lupus erythematosus (SLE)

Answer 130

* **Histatins** * Produced in the oral cavity. Active against pathogenic fungi, e.g. Candida albicans * **Cathelicidins** * LL-37 broad-spectrum antimicrobial activity against both Gram-negative and Gram-positive bacteria * (Defensins) * Two classes – α, β defensins

Answer 131

DNA and RNA synthesis